What causes electron to orbit the nucleus in an atom?

Question

What causes the electron to orbit the nucleus? Which is the force that causes it to do so? Is it related to the Electro - Magnetic force? .

Answer 1

It doesn't actually orbit the nucleus in the modern quantum mechanical understanding of the atom, although in a classical approximation, some properties relating to electron energy levels, etc. can be reproduced in terms of the picture of an "orbiting electron"*.

The reason you have an orbiting electron in the classical model is also related to this, as the only way the classical model can (try to) explain a stationary point-electron that isn't collapsing into the nucleus is to say the electron is spinning really fast. Note that "classical" in this sense also includes the Bohr model, which is entirely classical except it follows the old quantum rule $\int p\,dq=n\hbar$.

*as an example -- the energy levels in a quantum atom are given as $\sqrt{1-\alpha^2Z^2}$ where the fine structure constant $\alpha\approx1/137$, which is why you don't have atoms with more than 137 electrons. But in the classical picture, this gets re-interpreted as saying "the outer electron will have to move faster than light if you get more than 137 electrons", which has the same impact on the real-ness of the energy level.